I had to deal with Kudzu in Georgia and now I'm dealing with this.

Here's the problem. I've kept it out of my yard, but my neighbor seems to be fine with it overtaking his whole place. It runs over and under my fence, so I have to remove it occasionally. The bigger issue is that it is now going up into my Oak trees. My trees overhang my neighbor's property. I'd like to cut the Air Potato off where I can reach it so what is up in the trees will die.

Can I do that legally if the places I need to cut are on the other side of my fence?

spray it with roundoff, not an attorney but I think you can only cut it at your property line

Will spraying it with something like this harm my trees?

It's getting ugly. I can control what gets into my yard pretty easily, but my trees are getting it bad.